Graphics Programs Reference
In-Depth Information
UCS Based on Object Orientation
You can defi ne a UCS based on the orientation of an object. This is helpful when you want to
work on a predefi ned object to fi ll in details on its surface plane. The following steps are for
information only and aren't part of the tutorial. You can try this at another time when you aren't
working through an exercise.
Follow these steps to defi ne a UCS this way:
1. Click and hold the View tool in the Coordinates tool group of the Tool Sets palette and
release when the cursor is over the Object tool. You can also choose Tools New UCS
Object from the menu bar or type UCS OB ↵.
2. At the Select object to align UCS: prompt, pick the object that you want to use to
define the UCS. For example, you could click a 3D solid that you want to edit. The UCS
icon shifts to reflect the new coordinate system's orientation. Figure 20.11 shows an exam-
ple of using the OB (Object) option to select the edge of the chair back.
FIGURE 20.11
Using the Object
option of the
UCS command
to locate a UCS
When you use the
Object option, the
UCS will align to the
selected object.
Click this edge.
When you create a UCS using the Object option, the location of the UCS origin and its ori-
entation depend on how the selected object was created. Table 20.1 describes how an object can
determine the orientation of a UCS.
TABLE 20.1:
Effects of objects on the orientation of a UCS
OBJECT TYPE
UCS ORIENTATION
Arc
The center of the arc establishes the UCS origin. The X axis of the UCS passes
through the pick point on the arc.
Circle
The center of the circle establishes the UCS origin. The X axis of the UCS passes
through the pick point on the circle.
Dimension
The midpoint of the dimension text establishes the UCS origin. The X axis of the
UCS is parallel to the X axis that was active when the dimension was drawn.
Face (of a 3D solid)
The origin of the UCS is placed on a quadrant of a circular surface or on the cor-
ner of a polygonal surface.
 
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